Weigh Coffee Before or After Grinding? - Page 2

[another_jim]

I weigh before I grind. When I get a new grinder, I check the result by weighing afterwards as well. Here are the facts for most commercial grinders:

After the burrs are cleaned, around 5 grams of coffee will get compacted on the sweeper vanes in the grind chamber. Once this has happened, the weight of coffee going in, will on average equal the coffee coming out (how can it not?). I do not know whether the compacted coffee stays where it is, or if it exchanges mass with the coffee being ground. My sense is that there is very little exchange.

In addition to the compacted grounds, there is around 2 to 4 grams of loose grinds in the grind chamber and the deep recesses of the chute. The amount of this depends on the size of the grind chamber and burrs. It is worst for the conical grinders, since the 63 to 71mm burrs are housed in grind chambers also designed for larger 80 to 85mm flat burrs. The extra space fills with loose grinds.

If you have a full hopper, you will always get this loose coffee in your next shot. If you spoon the coffee into the throat, running on empty and several times will get the bulk of this out in the round in which it is ground.

If you weigh the coffee going in, you will usually get around +/- 1/2 gram variances in the final weight. Occasionally it can get worse, but I figure the +/- 1/2 grams is right 9 out of 10 times. If you are short in one grind, you will be long the next time -- there is obviously a serial correlation, since the amount coming out has to be the same in the long run as the amount going in.

My opinion on dose is the same as it is for temperature, pressure, and all the other stuff: close is good enough; don't waste your time and effort on getting it perfect; focus on the coffee instead.

Of course, if you really know for certain that 9.1 bar is better than 9.2, 201F better than 202, and 14.5 grams better than 15, go for it

[darrylr]

If you weigh the coffee going in, you will usually get around +/- 1/2 gram variances in the final weight. Occasionally it can get worse, but I figure the +/- 1/2 grams is right 9 out of 10 times.

Interesting. I have a Swift grinder and did some back to back measurements of it's dosing. It varies over a range of about +- .25g. Given it's sizeable burrs and long grind path I'd have expected it to be worse than what you quoted, assuming you were quoting based on grinders more like the Mazzer Mini or Macap M4. I wonder how the Swift achieves this.

Darryl

[Ken Fox]

Although I do advocate weighing after grinding, I would certainly not be extremely anal about it. If you are going to weigh afterwards, you do need an accurate scale, and I'd suggest one that can weigh down to 0.1g, which in fact will give you a usable accuracy to about 1/3 or 1/2 of a gram. Scales like this can be purchased for as little as $12, as with the link I've posted previously from an online vendor in Hong Kong.

I don't fuss over 0.3g, but I do add or remove coffee if it is more than that. To accomplish this I have the ramekin or other vessel (sometimes a bottomless PF) on the scale which was previously tare'd. I remove excess coffee with the tip of a teaspoon.

Since I have started weighing the grinds, a practice I considered extremely anal before, I would estimate that the total extra time I spend per day in making 3-5 double shots is less than one minute. I have virtually eliminated sink shots with this approach (which includes dosing in the ~14g range instead of ~19g as before) and as a result, timewise, the whole enterprise is a wash since I almost never have to remake a shot that was ruined by channeling, since this basically does not occur with Italian-ish dosing.

As to Jim's comment about eliminating the stale grinds when one uses an empty hopper vs. always being stuck with them when the hopper is more full, I think this is a bit misleading, since it is going to be very grinder dependent, and in any event something is going to have to be there to push out the remaining grinds after they exit the burrs. That "something" is going to be coffee. Air is not going to push the coffee out. I really doubt that this is a distinction in favor of any particular approach, full or empty hopper, that one prefers.

Since the amount of said waste is going to be grinder-design dependent, I have noticed that I have a bit more waste with my Compak conical grinder than with my 2 Cimbali hybrid conical/planar Max grinders. If I did not salvage the exit chute grinds for each shot, the Compak would be incredibly wasteful for home use if one insisted on removing all the "stale" grinds before grinding for each and every shot, assuming that shots are going to be made sporadically and not all at the same time. All of these commercial grinders are designed for consistent use, and by using them in our homes we are getting both the advantages and disadvantages of using commercial equipment in a home setting. However we adapt to these design peculiarities for our particular uses, will have both advantages and disadvantages, as well.

ken

[Rosemary]

But they don't, especially if you are talking about a commercial level grinder with burr diameter of 64mm or more. If you try this repeatedly and weigh the results, you will find that there is an "average" loss with most grinders, but sometimes you get more out than you put in (e.g. there is some leftover from before that you thought you had evacuated) or you get a lot less, like 3g swallowed up for no apparent reason.

ken

I have wondered if the age of coffee affects the retention of grounds - I think it retains more the fresher the beans are. Has anyone else found this?

I have also wondered if the humidity has an effect on static and retention of grounds.

Rosemary

[Marshall]

First there is the fundamental question of whether you need to weigh at all and what your approach is to home espresso. I think there are two broad models espoused on the Internet forums.

Weighing comes from the "laboratory" model. It emphasizes careful measurement and reproducibility. I think that anyone who weighs their coffee one shot at a time is implicitly adopting the science lab as his or her model.

The other model is an espresso shop with high standards ("third wave," if you like). For myself, I tend to think what works for the best baristas in a well-run shop should work for me, and by and large, it has. So, after using a digital scale for a few days to get a good idea of what a 17 or 22-gram shot looks like, I retired my scale to postage meter duty and measure my doses by automatic timer. Vivre la difference!

[HB]

I think that anyone who weighs their coffee one shot at a time is implicitly adopting the science lab as his or her model... So, after using a digital scale for a few days to get a good idea of what a 17 or 22-gram shot looks like, I retired my scale to postage meter duty and measure my doses by automatic timer. Vivre la difference!

When it comes to developing barista skills, I'm all for going au naturel with regular recalibrations (a la Exercises for tuning your barista techniques). However, I think that your dosing by automatic timer isn't appreciably different from those who weigh, except the timer setting may have to be reset for different beans to produce the same weight due to differences in bean hardness/moisture. Why not ditch the timer? Few third wave espresso shops I've seen use them except to prevent overruns.

[Marshall]

However, I think that your dosing by automatic timer isn't appreciably different from those who weigh, except the timer setting may have to be reset for different beans to produce the same weight due to differences in bean hardness/moisture. Why not ditch the timer? Few third wave espresso shops I've seen use them except to prevent overruns.

To prevent overruns!

I should point out that my timer is a Waring appliance timer that directly controls the grinder. I just touch a button once on the timer, which turns the grinder on and then turns it off in 11 or 12 seconds (depending on grind). It does the same thing that the built-in timers do on the new "E" Mazzers.

Timing is also a good way to track wear of the burrs. Michael Teahan recommends replacing burrs when grinds take 20% longer than when new. I'm expecting to replace my burrs in 2018 and don't want to be late!

In any event, pushing one button seems a long way off from measuring out beans into a basket, weighing them, putting the excess back in a jar, re-weighing them, putting the basket in the portafilter.....

[Ken Fox]

In any event, pushing one button seems a long way off from measuring out beans into a basket, weighing them, putting the excess back in a jar, re-weighing them, putting the basket in the portafilter.....

that would be way too tedious for me, if I did it that way. I also think that constantly changing bean types in a given grinder is probably going to produce inferior results, for a whole host of reasons even though this technique is practiced by and recommended by people that I respect (some are even my friends ). The reasons why I think constantly changing bean types in a grinder is a bad idea include:

(1) There is no way to weigh down the last part of a bean mass you are grinding this way, because whatever you have in there to weigh down the beans (tamper, spice jar, what-have-you) will not be in contact with beans at the end, it will instead be riding on top of a bolt or burr carrier or something else when there are still several grams of coffee in the entry chute waiting to be ground. This means, assuming that you do weigh down the beans when you start, there will be larger variation in your grind particle sizes for these last few grams and the overall dose of ground coffee will be less homogeneous in grind size, if this matters.

(2) It remains unproven that you can flush a given quantity of beans through a grinder and get back out what you put in, even if the weights of the pre-ground beans and of the grinds come out to be identical, and if you "salvage" the chute grinds with a chopstick or other implement. Most probably there are a few grams of coffee from the last grind that are sitting along the path and they get pushed out later, for the next shot, which then ends up being a melange of old grinds of one coffee mixed in with new grinds of another, and with more variable particle sizes as in #1.

I'd much rather change coffees in grinders much less often, flush out a couple of grams of grinds at the start of grinding to both flush the recesses of trapped grinds and clean the doser out.

So what I do is to keep the hopper sufficiently full that enough weight is present on the bean column to prevent popcorning and changes in grind requiring adjustments.; for me this is generally enough coffee for at least one more shot than the one I am making, except when I'm ending a batch of a given coffee. SO:

what I do is to pulse the grinder on for a second, discharge the grinds through the doser, then take the Tare-d receptacle and fill it to where I think it needs to be. I then put it on the scale and if it needs a little more, I pulse for second or two (depending on how low I am in the weight), which if low generally will get me to where I want to be or slightly over. If over, either initially or after a 2nd go round, I then use a teaspoon tip to remove excess grinds noting the weight on the display of the scale. The coffee then goes into the PF in a couple of teaspoonfuls, plus pouring the excess in directly from the receptacle (generally a ramekin). I then proceed to put 1.2 microseconds into my tamping, then pull the shot. I'd bet my total shot preparation time is less than yours, even with the scale!

ken

[cannonfodder]

Isn't the definition of a barista 'I thwack therefore I am'?

I just grind, thwack and eyeball with an occasional scale check when I use a new coffee. I usually hit well within a half gram, usually more like one quarter using that method. But when I do break out the scale, it is post grind measurement not pre.